Solid electrolytic capacitor

ABSTRACT

A solid electrolytic capacitor includes a capacitor element, an outer package member covering the capacitor element, an anode terminal, and a cathode terminal. The capacitor element includes an anode body, an anode member buried in the anode body, a dielectric layer formed on part of a surface of the anode body, an electrolyte layer formed on the dielectric layer, and a cathode layer formed on the electrolyte layer. The anode member has a lower end portion exposed at a lower surface of the anode body. The anode terminal is electrically connected to the lower end portion, and has a surface partially exposed at a lower surface of the outer package member. The cathode terminal is electrically connected to the cathode layer at a position below the lower surface of the anode body, and has a surface partially exposed at the lower surface of the outer package member.

INCORPORATION BY REFERENCE

Japanese patent application Number 2010-277433, upon which this patentapplication is based, is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a solid electrolytic capacitor.

2. Description of Related Art

FIG. 16 is a sectional view of a conventional solid electrolyticcapacitor. As shown in FIG. 16, the conventional solid electrolyticcapacitor includes a lead-type capacitor element 81, an outer packagemember 82 covering the capacitor element 81, an anode terminal 83, and acathode terminal 84. The capacitor element 81 includes an anode body 811in the form of a rectangular parallelepiped, an anode lead 812 implantedin the anode body 811, a dielectric layer 813 formed on the outercircumference of the anode body 811, an electrolyte layer 814 formed onthe dielectric layer 813, and a cathode layer 815 formed on theelectrolyte layer 814. The anode and cathode terminals 83 and 84 arespaced apart from each other in a predetermined direction 89 (horizontaldirection in the plane of FIG. 16). Part of a surface of the anodeterminal 83 and part of surface of the cathode terminal 84 are exposedat a lower surface 82 a of the outer package member 82. These exposedsurfaces of the anode and cathode terminals 83 and 84 form anode andcathode terminal surfaces 830 and 840 of the solid electrolyticcapacitor respectively.

In the conventional solid electrolytic capacitor shown in FIG. 16, thecapacitor element 81 is placed on the anode and cathode terminals 83 and84 in such a posture that a pulled-out portion 812 a of the anode lead812 pointing in the direction 89. The pulled-out portion 812 a and theanode terminal 83 are electrically connected to each other through aconductive pillow member 85. Further, the cathode layer 815 and thecathode terminal 84 are electrically connected to each other through aconductive adhesive agent (not shown) provided therebetween. The solidelectrolytic capacitor is given a current path 86 extending from theanode terminal surface 830 through the anode lead 812 to reach thecathode terminal surface 840.

In the conventional solid electrolytic capacitor shown in FIG. 16, theanode lead 812 is pulled out substantially through the center of asurface 811 b as part of the outer circumference of the anode body 811through which the anode lead 812 is implanted. So, the aforementionedposture of the capacitor element 81 places the pulled-out portion 812 aat a position higher than a lower surface 811 a of the anode body 811.To be specific, the pulled-out portion 811 a is placed far above theanode terminal surface 830.

So, the conventional solid electrolytic capacitor finds difficulty inshortening the current path 86, placing limitations on reduction of ESL(equivalent series inductance) and/or ESR (equivalent seriesresistance).

It is preferable that the anode terminal 83 be placed near thepulled-out portion 812 a in order to minimize the ESL and/or ESR of asolid electrolytic capacitor. So, if the pulled-out portion 812 a ispointed in the direction 89 as in the conventional solid electrolyticcapacitor (FIG. 16), the anode terminal 83 should be provided near thesurface 811 b of the anode body 811. As a result, design of the anodeand cathode terminals 83 and 84 including arrangement of the anode andcathode terminals 83 and 84, and connections between the anode andcathode terminals 83 and 84 and the capacitor element 81, should be madewith a low degree of freedom.

In addition, in the conventional solid electrolytic capacitor shown inFIG. 16, a side surface of the pulled-out portion 812 a of the anodelead 812 is electrically connected to a tip end surface of the pillowmember 85. This makes a contact area between the anode lead 812 and thepillow member 85 small so high electrical resistance is easily generatedbetween the anode lead 812 and the pillow member 85, placing an obstacleto reduction of ESR.

SUMMARY OF THE INVENTION

A solid electrolytic capacitor of the invention includes a capacitorelement, an outer package member covering the capacitor element, ananode terminal, and a cathode terminal. The capacitor element includesan anode body, an anode member buried in the anode body, a dielectriclayer, an electrolyte layer formed on the dielectric layer, and acathode layer formed on the electrolyte layer. The anode member has alower end portion exposed at a lower surface of the anode body. Thedielectric layer is formed on part of a surface of the anode body thatis in a region different from a region where the anode body contacts theanode member. The anode terminal is electrically connected to the lowerend portion of the anode member, and has a surface partially exposed ata lower surface of the outer package member. The cathode terminal iselectrically connected to the cathode layer at a position below thelower surface of the anode body, and has a surface partially exposed atthe lower surface of the outer package member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a solid electrolytic capacitor of anembodiment of the invention;

FIG. 2 is a bottom view of the solid electrolytic capacitor;

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 2;

FIG. 5 is a perspective view used to explain an anode forming step thatis part of a method of manufacturing the solid electrolytic capacitor;

FIG. 6 is a view used to explain a dielectric layer forming step that ispart of the manufacturing method;

FIG. 7 is a view used to explain an electrolyte layer forming step thatis part of the manufacturing method;

FIG. 8 is a perspective view used to explain a first stage of an elementmounting step that is part of the manufacturing method;

FIG. 9 is a perspective view used to explain a second stage of theelement mounting step that is part of the manufacturing method;

FIG. 10 is a perspective view used to explain an outer package formingstep that is part of the manufacturing method;

FIG. 11 is a bottom view of a first modification of the solidelectrolytic capacitor;

FIG. 12 is a sectional view taken along line XII-XII of FIG. 11;

FIG. 13 is a sectional view taken along line XIII-XIII of FIG. 11;

FIG. 14 is a bottom view of a second modification of the solidelectrolytic capacitor;

FIG. 15 is a sectional view of a different modification of the solidelectrolytic capacitor; and

FIG. 16 is a sectional view of a conventional solid electrolyticcapacitor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a perspective view of a solid electrolytic capacitor of anembodiment of the invention. FIG. 2 is a bottom view of the solidelectrolytic capacitor. The solid electrolytic capacitor shown in FIGS.1 and 2 includes a solid electrolytic capacitor element 1, an outerpackage member 2 covering the capacitor element 1, an anode terminal 3,and a cathode terminal 4. The outer package member 2 is made of resinsuch as an epoxy resin.

FIGS. 3 and 4 are sectional views taken along lines and IV-IV of FIG. 2respectively. As shown in FIGS. 3 and 4, the capacitor element 1 has ananode body 11 in the form of a rectangular parallelepiped, and an anodemember 12 buried in the anode body 11. The outer circumference of theanode body 11 includes a lower surface 11 a (see FIG. 3), and first andsecond side surfaces 11 b and 11 c (see FIG. 4) substantially oppositeeach other. The anode member 12 extends between the first and secondside surfaces 11 b and 11 c of the anode body 11 as shown in FIG. 4. Alower end portion 121 of the anode member 12 projects from the lowersurface 11 a of the anode body 11 as shown in FIG. 3. So, the lower endportion 121 of the anode member 12 is exposed at the lower surface 11 aof the anode body 11.

The anode body 11 is composed of a porous sintered body made of a valveacting metal. The anode member 12 is made of a valve acting metal thetype of which is the same as or different from the valve acting metalconstituting the anode body 11. As a result, the anode body 11 and theanode member 12 are electrically connected to each other. Examples ofthe valve acting metal constituting the anode body 11 and the anodemember 12 include tantalum, niobium, titanium, and aluminum.

As shown in FIGS. 3 and 4, a dielectric layer 13 is formed on part ofthe outer circumference of the anode body 11 that is in a regiondifferent from a region R where the anode member 12 is exposed (see FIG.3), namely on part of a surface of the anode body 11 that is in a regiondifferent from a region where the anode body 11 contacts the anodemember 12. The dielectric layer 13 is formed by electrochemicallyoxidizing the outer circumference of the anode body 11. In theembodiment, part of the dielectric layer 13 is also formed on a surfaceof the root of the lower end portion 121 (exposed portion) of the anodemember 12.

Also, as shown in FIGS. 3 and 4, an electrolyte layer 14 is formed onthe dielectric layer 13, and a cathode layer 15 is formed on theelectrolyte layer 14. The electrolyte layer 14 is made of an electrolytematerial that can be solidified on the dielectric layer 13. Theelectrolyte material may be a conductive inorganic material such asmanganese dioxide, or a conductive organic material such as TCNQ(tetracyano-quinodimethane) complex salt and conductive polymer. Thecathode layer 15 is composed of a carbon layer (not shown) formed on theelectrolyte layer 14, and a silver paint layer (not shown) formed on thecarbon layer. The electrolyte layer 14 and the cathode layer 15 areelectrically connected to each other.

As shown in FIG. 3, the anode and cathode terminals 3 and 4 are buriedin the outer package member 2, and are spaced apart from each other in adirection 92 substantially perpendicular to a direction 91 (see FIG. 4)in which the anode member 12 extends. The anode terminal 3 iselectrically connected to the lower end portion 121 of the anode member12, whereas the cathode terminal 4 is electrically connected to thecathode layer 15 at a position below the lower surface 11 a of the anodebody 11. Electrical connection between the anode terminal 3 and thelower end portion 121 is formed by performing welding on surfaces of theanode terminal 3 and the lower end portion 121 contacting each other. Anend portion of the cathode ten final 4 closer to the anode terminal 3 isprovided with a bent part 41 in the form of an inverted L. The bent part41 is formed by deforming the cathode terminal 4 by bending. The bentpart 41 and the cathode layer 15 are electrically connected to eachother through a conductive adhesive agent (not shown) providedtherebetween.

Part of a surface of the anode terminal 3 and part of a surface of thecathode terminal 4 are exposed at a lower surface 2 a of the outerpackage member 2. These exposed surfaces of the anode and cathodeterminals 3 and 4 form anode and cathode terminal surfaces 30 and 40 ofthe solid electrolytic capacitor respectively. Like the arrangement ofthe anode and cathode terminals 3 and 4 relative to each other, theanode and cathode terminal surfaces 30 and 40 of the embodiment arespaced apart from each other in the direction 92.

A method of manufacturing the aforementioned solid electrolyticcapacitor is described in detail next by referring to drawings. Themanufacturing method includes an element forming step, an elementmounting step, an outer package forming step, and a cutting stepperformed in this order. The element forming step is a step of formingthe capacitor element 1, and which includes an anode forming step, adielectric layer forming step, an electrolyte layer forming step, acathode layer forming step, and a peeling step performed in this order.

FIG. 5 is a perspective view used to explain the anode forming step. Asshown in FIG. 5, in the anode forming step, a powder molded body 50 tobecome the anode body 11 is prepared. The powder molded body 50 is madeof powder of a valve acting metal. A metallic member 51 in the form of aprism to become the anode member 12 is provided at a predeterminedposition of the powder molded body 50. More specifically, the powder ispoured in a die of a predetermined shape (not shown) and part of themetallic member 51 is inserted into the die, and thereafter, pressure isapplied to the die to press the powder into a solid form.

In the anode forming step, the powder is pressed into a solid form suchthat the powder molded body 50 is formed into a rectangularparallelepiped, more specifically that the powder molded body 50 isgiven an outer circumference with a first molded surface 50 a to becomethe lower surface 11 a of the anode body 11, and second and third moldedsurfaces 50 b and 50 c to become the first and second side surfaces 11 band 11 c of the anode body 11 respectively. Further, the metallic member51 is provided to the powder molded body 50 such that the metallicmember 51 extends from the second molded surface 50 b through the thirdmolded surface 50 c to a position above the third molded surface 50 c,and that a side edge portion 511 of the metallic member 51 to become thelower end portion 121 of the anode member 12 projects from the firstmolded surface 50 a of the powder molded body 50.

In the anode forming step, the powder molded body 50 is sintered byburning the powder molded body 50 and the metallic member 51 together ata predetermined temperature. As a result, the powder molded body 50becomes a porous sintered body to form the anode body 11.

FIG. 6 is a view used to explain the dielectric layer forming step. Asshown in FIG. 6, in the dielectric layer forming step, a processing bath71 filled with an electrolytic solution 710 is prepared first. A cathodeplate 711 is provided in the electrolytic solution 710. A solution suchas a phosphorus acid solution and an adipic acid solution is used as theelectrolytic solution 710. Next, as shown in FIG. 6, the anode body 11is dipped in the electrolytic solution 710, and thereafter, a voltage V1is applied between the metallic member 51 and the cathode plate 711 tocause a current to flow in the anode body 11. In response, the outercircumference of the anode body 11 is electrochemically oxidized to forman oxide film to become the dielectric layer 13 on the outercircumference of the anode body 11. At this time, an oxide film is alsoformed on part of an exposed surface of the metallic member 51 that isin a region dipped in the electrolytic solution 710.

Next, in the electrolyte layer forming step, a conductive precoat layer(not shown) is formed on the dielectric layer 13. The precoat layer ismade of a conductive material such as a conductive polymer, and isformed by chemical polymerization.

In the electrolyte layer forming step, a processing bath 72 filled withan electropolymerization solution 720 is further prepared as shown inFIG. 7. A cathode plate 721 is provided in electropolymerizationsolution 720. The electropolymerization solution 720 is made of aconductive organic material such as monomer to become a conductivepolymer. Next, the anode body 11 is dipped in the electropolymerizationsolution 720. Then, an external electrode 722 is caused to electricallycontact the precoat layer in the electropolymerization solution 720, anda voltage V2 is applied between the external electrode 722 and thecathode plate 721. In response, a current flows in the precoat layer toform an electropolymerized film on the precoat layer. As a result, theelectrolyte layer 14 with the precoat layer and the electropolymerizedfilm is formed on the dielectric layer 13.

In the cathode layer forming step, the anode body 11 is first dipped ina carbon paste to form a carbon layer (not shown) on the electrolytelayer 14. Next, the anode body 11 is dipped in a silver paste to form asilver paint layer (not shown) on the carbon layer. As a result, thecathode layer 15 with the carbon layer and the silver paint layer isformed on the electrolyte layer 14.

In the peeling step, laser is applied to parts of the dielectric layer13, the electrolyte layer 14, and the cathode layer 15 existing on asurface of the side edge portion 511 of the metallic member 51 (see FIG.5). This peels off the dielectric layer 13, the electrolyte layer 14,and the cathode layer 15 on this surface to expose a surface of themetallic member 51. Then, the metallic member 51 is cut along line C ofFIG. 5. As a result, part of the metallic member 51 remaining on theanode body 11 becomes the anode member 12 to finish formation of thecapacitor element 1.

FIGS. 8 and 9 are perspective views used to explain first and secondstages of the element mounting step respectively. First, in the elementmounting step, anode and cathode frames 61 and 62 to become the anodeand cathode terminals 3 and 4 respectively are prepared as shown in FIG.8. The anode and cathode frames 61 and 62 are spaced apart from eachother in a predetermined direction 93, and lower surfaces 61 a and 62 aof the anode and cathode frames 61 and 62 respectively are arranged onthe same plane. An end portion of the cathode frame 62 closer to theanode frame 61 is provided with the bent part 41 in the form of aninverted L. The bent part 41 is formed by deforming the cathode frame 62by bending. The height T2 of the bent part 41 is determined such that adegree of projection T1 of the anode member 12 from a lower surface 1 aof the capacitor element 1 is substantially the same as a sum of theheight T2 and the thickness of a conductive adhesive agent (not shown)to be provided between the bent part 41 and the cathode layer 15.

Next, the capacitor element 1 is mounted on the anode and cathode frames61 and 62 in the following manner as shown in FIG. 9. The lower surface1 a of the capacitor element 1 faces the frames 61 and 62, and thedirection 91 in which the anode member 12 extends is substantiallyperpendicular to the direction 93 in which the anode and cathode frames61 and 62 are aligned. The anode member 12 faces the anode frame 61.Further, part of the lower surface 1 a of the capacitor element 1 thatis in a region different from a region where the anode member 12 isprovided faces the bent part 41 of the cathode frame 62. In addition, aconductive adhesive agent (not shown) is provided between surfaces ofthe bent part 41 and the cathode layer 15 facing each other, therebyelectrically connecting the cathode frame 62 and the cathode layer 15 toeach other.

The degree of projection T1 of the anode member 12 is substantially thesame as a sum of the height T2 of the bent part 41 and the thickness ofthe aforementioned conductive adhesive agent. So, mounting the capacitorelement 1 makes the lower end portion 121 of the anode member 12 contactthe anode frame 61. In the element mounting step, surfaces of the anodeframe 61 and the anode member 12 contacting each other are subjected towelding to electrically connect the anode frame 61 and the anode member12 to each other.

FIG. 10 is a perspective view used to explain the outer package foilling step. In the outer package forming step shown in FIG. 10, thecapacitor element 1 is covered with the outer package member 2 by usinga molding technique. At this time, the lower surfaces 61 a and 62 a ofthe anode and cathode frames 61 and 62 respectively are exposed at thelower surface 2 a of the outer package member 2. Resin such as an epoxyresin is used to form the outer package member 2.

In the cutting step, the anode and cathode frames 61 and 62 are cut atpositions D and E respectively shown in FIG. 10. As a result, part ofthe anode frame 61 left in the outer package member 2 becomes the anodeterminal 3, and part of the cathode frame 62 left in the outer packagemember 2 becomes the cathode terminal 4 to finish formation of the solidelectrolytic capacitor.

In the solid electrolytic capacitor described above, the parts of thesurfaces of the anode and cathode terminals 3 and 4 are exposed at thelower surface 2 a of the outer package member 2. These exposed surfacesof the anode and cathode terminals 3 and 4 form the anode and cathodeterminal surfaces 30 and 40 of the solid electrolytic capacitorrespectively. Further, this solid electrolytic capacitor is given acurrent path 6 extending from the anode terminal surface 30 through theanode member 12 to the cathode terminal surface 40 as shown in FIG. 3.

In the aforementioned solid electrolytic capacitor, the lower endportion 121 of the anode member 12 projects from the lower surface 11 aof the anode body 11. This places the exposed portion (lower end portion121) of the anode member 12 at a position below the lower surface 11 aof the anode body 11 to shorten a distance of the exposed portion to thelower surface 2 a of the outer package member 2. Thus, in this solidelectrolytic capacitor, the distance of the exposed portion to the anodeterminal surface 30 is shorter than a corresponding distance in theconventional solid electrolytic capacitor shown in FIG. 16, therebymaking the current path 6 shorter. As a result, the solid electrolyticcapacitor achieves reduction of ESL and/or reduction of ESR.

In the aforementioned solid electrolytic capacitor, both the anode andcathode terminals 3 and 4 extend to the lower surface 2 a of the outerpackage member 2 without passing through the side surfaces of the outerpackage member 2 to expose the parts of the surfaces of the anode andcathode terminals 3 and 4 at the lower surface 2 a. So, this solidelectrolytic capacitor shortens the length of a path in the anodeterminal 3 between the anode terminal surface 30 and the exposed portion(lower end portion 121) of the anode member 12, and shortens the lengthof a path in the cathode terminal 4 between the cathode terminal surface40 and the cathode layer 15. As a result, the solid electrolyticcapacitor achieves further reduction of ESL and/or reduction of ESR.

In the aforementioned solid electrolytic capacitor, the anode member 12extends between the first and second side surfaces 11 b and 11 c of theanode body 11, so the region R of the anode member 12 where the anodemember 12 is exposed spreads in the direction 91 in which the anodemember 12 extends. In this solid electrolytic capacitor, the anode andcathode terminals 3 and 4 are spaced apart from each other in thedirection 92 substantially perpendicular to the direction 91. So, acontact area between the exposed portion (lower end portion 121) and theanode terminal 3 can be increased by making the anode terminal 3 spreadfurther in the direction 91. Increasing this contact area reduceselectrical resistance to be generated between the anode member 12 andthe anode terminal 3. As a result, the solid electrolytic capacitorachieves further reduction of ESR.

If the anode and cathode terminals 3 and 4 are spaced apart from eachother in a direction substantially the same as the direction 91 in whichthe anode member 12 extends, connection between the anode terminal 3 andthe anode member 12 may be limited only to part of the exposed portion(lower end portion 121). However, the aforementioned solid electrolyticcapacitor is free from such limitations, and allows the anode terminal 3to be connected to the entire exposed portion of the anode member 12. Asa result, design of the anode and cathode terminals 3 and 4 includingarrangement of the anode and cathode terminals 3 and 4, and connectionsbetween the anode and cathode terminals 3 and 4 and the capacitorelement 1, can be made with a high degree of freedom. As an example, theanode and cathode terminals 3 and 4 can be designed in a manner shown ina second modification (FIG. 14) described later.

The structure of the embodiment is an example of a preferable structure,and is not intended to exclude a structure such as that of a firstmodification described later where the anode and cathode terminals 3 and4 are spaced apart from each other in a direction substantially the sameas the direction 91 in which the anode member 12 extends.

Also, in the aforementioned solid electrolytic capacitor, the lower endportion 121 of the anode member 12 projects from the lower surface 11 aof the anode body 11. This makes it possible to easily form electricalconnection between the exposed portion (lower end portion 121) and theanode terminal 3 during the manufacturing process of the solidelectrolytic capacitor.

FIG. 11 is a bottom view of the first modification of the aforementionedsolid electrolytic capacitor. FIGS. 12 and 13 are sectional views takenalong lines XII-XII and XIIII-XIII of FIG. 11 respectively. In theaforementioned solid electrolytic capacitor, the anode and cathodeterminals 3 and 4 may be spaced apart from each other in a directionsubstantially the same as the direction 91 in which the anode member 12extends as shown in FIGS. 11 and 12.

As shown in FIG. 12, the anode member 12 extends from the first sidesurface 11 b to a predetermined position toward the second side surface11 c of the anode body 11, but does not reach the second side surface 11c. Further, the lower end portion 121 of the anode member 12 projectsfrom the lower surface 11 a of the anode body 11. The anode terminal 3extends in the direction 92 substantially perpendicular to the direction91 as shown in FIG. 11. Further, the anode terminal 3 is electricallyconnected to the lower end portion 121 of the anode member 12 in aposition near the first side surface 11 b of the anode body 11 as shownin FIG. 12.

The cathode terminal 4 is spaced apart from the anode terminal 3 in thedirection 91, and which extends substantially parallel to the anodeterminal 3 as shown in FIG. 11. The cathode terminal 4 is spaced belowthe anode member 12 as shown in FIG. 12. Further, as shown in FIGS. 11and 13, an outer periphery of the cathode terminal 4 closer to the anodeterminal 3 is provided with first electrical connections 421 placed attwo positions on the outer periphery between which the anode member 12is placed. The first electrical connections 421 are each in the form ofan inverted L, and extend toward the anode terminal 3. An outerperiphery of the cathode terminal 4 farther from the anode terminal 3 isprovided with second electrical connections 422 placed at two positionson the outer periphery between which the anode member 12 is placed. Thesecond electrical connections 422 are each in the form of an inverted L,and extend in a direction away from the anode terminal 3. The secondelectrical connections 422 are coupled to each other through a couplingpart 423.

The first electrical connections 421, the second electrical connections422, and the coupling part 423 are each electrically connected to thecathode layer 15 at a position below the lower surface 11 a of the anodebody 11. This makes electrical connection of the cathode terminal 4 tothe cathode layer 15 through the first electrical connections 421, thesecond electrical connections 422, and the coupling part 423.

In the solid electrolytic capacitor of the first modification, part of asurface of the anode terminal 3 and part of a surface of the cathodeterminal 4 are exposed at the lower surface 2 a of the outer packagemember 2. These exposed surfaces of the anode and cathode terminals 3and 4 form the anode and cathode terminal surfaces 30 and 40 of thesolid electrolytic capacitor respectively. Further, this solidelectrolytic capacitor is given a current path 6 extending from theanode terminal surface 30 through the anode member 12 to the cathodeterminal surface 40 as shown in FIG. 12.

Like in the aforementioned solid electrolytic capacitor, the lower endportion 121 of the anode member 12 projects from the lower surface 11 aof the anode body 11 in the solid electrolytic capacitor of the firstmodification. This places the exposed portion (lower end portion 121) ofthe anode member 12 at a position below the lower surface 11 a of theanode body 11 to shorten a distance of the exposed portion to the lowersurface 2 a of the outer package member 2. Thus, in the solidelectrolytic capacitor of the first modification, the distance of theexposed portion to the anode terminal surface 30 is shorter than acorresponding distance in the conventional solid electrolytic capacitorshown in FIG. 16, thereby making the current path 6 shorter. As aresult, the solid electrolytic capacitor achieves reduction of ESLand/or reduction of ESR.

FIG. 14 is a bottom view of the second modification of theaforementioned solid electrolytic capacitor. As shown in FIG. 14, theaforementioned solid electrolytic capacitor may include a plurality ofterminal units 63 arranged in the direction 91 in which the anode member12 extends and each of which is composed of the anode and cathodeterminals 3 and 4. The arrangement of two adjacent ones of the terminalunits 63 relative to each other is such that the anode terminal 3belonging to one of the adjacent terminal units 63 and the cathodeterminal 4 belonging to the other of the adjacent terminal units 63 aresubstantially parallel to each other.

In the solid electrolytic capacitor of the second modification, inresponse to application of a voltage to each of the terminal units 63,currents in opposite directions flow in the anode and cathode terminals3 and 4 substantially parallel to each other that belong to two adjacentones of the terminal units 63. So, magnetic fields generated by thesecurrents cancel each other out, thereby generating current cancelingeffect in the solid electrolytic capacitor. As a result, the solidelectrolytic capacitor of the second modification achieves furtherreduction of ESL.

In the solid electrolytic capacitor of the second modification,regarding two adjacent ones of the terminal units 63 relative to eachother, it is preferable that a distance H1 between the anode and cathodeterminals 3 and 4 belonging to each of the adjacent terminal units 63 besubstantially the same as a distance H2 between the adjacent terminalunits 63 as shown in FIG. 14, or smaller than the distance H2. This canmake the distance H1 smaller to make the current path 6 (see FIG. 3)still shorter. As a result, the solid electrolytic capacitor achievesfurther reduction of ESL and/or reduction of ESR.

The structure of each part of the invention is not limited to that shownin the embodiment described above. Various modifications can be devisedwithout departing from the technical scope recited in claims. By way ofexample, in the aforementioned solid electrolytic capacitor, the lowerend portion 121 of the anode member 12 may not project from the lowersurface 11 a of the anode body 11, namely, the lower end surface of theanode member 12 and the lower surface 11 a of the anode body 11 may bearranged on the same plane. This structure also makes a distance of theexposed portion of the anode member 12 to the anode terminal surface 30shorter than a corresponding distance in the conventional solidelectrolytic capacitor shown in FIG. 16. Thus, the current path 6 isshortened, so that the solid electrolytic capacitor achieves reductionof ESL and/or reduction of ESR. Further, design of the anode and cathodeterminals 3 and 4 can be made with a high degree of freedom. Meanwhile,it is preferable that the lower end portion 121 of the anode member 12project from the lower surface 11 a of the anode body 11. The reasontherefor is as follows. The lower end portion 121 may be shifted in adirection same as or opposite the direction 93 from a predeterminedposition on the anode frame 61 when the capacitor element 1 is mountedon the anode and cathode frames 61 and 62 in the element mounting step(see FIGS. 8 and 9). Even in this case, if the lower end portion 121projects from the lower surface 11 a of the anode body 11 as shown inFIG. 3, the anode frame 61 and the cathode layer 15 will not contacteach other to prevent electrical short therebetween.

In the aforementioned solid electrolytic capacitor, the anode member 12extends from the first side surface 11 b toward the second side surface11 c of the anode body 11. However, the anode member 12 may not reachthe second side surface 11 c. Also, the anode member 12 may be ametallic member in the form of a cylindrical column (such as a metalwire), or a metallic member in the form of a prism. Meanwhile, it ispreferable that the anode member 12 be not in the form of a cylindricalcolumn, but in the form of a prism, specifically in the form of aquadrangular prism. The reason therefor is that this increases a contactarea between the anode member 12 and the anode terminal 3 to achievereduction of ESR of the solid electrolytic capacitor.

Additionally, in the aforementioned solid electrolytic capacitor, theanode terminal 3 may include upper and lower stage parts 31 and 32formed by deforming the anode terminal 3 into the shape of a crank bybending as shown in FIG. 15. In this structure, the upper stage part 31has an upper surface electrically connected to the lower end portion 121of the anode member 12, and a lower surface covered with the outerpackage member 2. Further, the lower stage part 32 has a lower surfaceexposed at the lower surface 2 a of the outer package member 2, and thisexposed surface forms the anode terminal surface 30 of the solidelectrolytic capacitor. In the solid electrolytic capacitor shown inFIG. 15, covering the lower surface of the upper stage part 31 with theouter package member 2 makes the anode terminal 3 less likely to beseparated from the outer package member 2. In the solid electrolyticcapacitor shown in FIG. 15, a distance L1 between the lower surface 1 aof the capacitor element 1 and the upper surface of the lower stage part32 of the anode terminal 3 is substantially the same as a sum of theheight T2 of the bent part 41 of the cathode terminal 4 and thethickness of a conductive adhesive agent (not shown) provided betweenthe bent part 41 and the cathode layer 15.

The invention claimed is:
 1. A solid electrolytic capacitor, comprising:a capacitor element including an anode body, an anode member buried inthe anode body, a dielectric layer, an electrolyte layer formed on thedielectric layer, and a cathode layer formed on the electrolyte layer,the anode member having a lower end portion exposed at a lower surfaceof the anode body, the dielectric layer being formed on part of asurface of the anode body that is in a region different from a regionwhere the anode body contacts the anode member; an outer package membercovering the capacitor element; an anode terminal electrically connectedto the lower end portion of the anode member, and having a surfacepartially exposed at a lower surface of the outer package member; and acathode terminal electrically connected to the cathode layer at aposition below the lower surface of the anode body, and having a surfacepartially exposed at the lower surface of the outer package member,wherein the anode body has an outer circumference including a first sidesurface and a second side surface substantially opposite each other, theanode member extends between the first and second side surfaces, andincludes a first edge surface and a second edge surface, the first edgesurface being exposed at the first side surface and the second edgesurface being exposed at the second side surface, and part of thedielectric layer is formed on the first edge surface whereas thedielectric layer is not formed on the second edge surface.
 2. The solidelectrolytic capacitor according to claim 1, wherein the anode andcathode terminals are spaced apart from each other in a directionsubstantially perpendicular to a direction in which the anode memberextends.
 3. The solid electrolytic capacitor according to claim 2,wherein a plurality of terminal units is arranged in the direction inwhich the anode member extends, each of the terminal units beingcomposed of the anode and cathode terminals.
 4. The solid electrolyticcapacitor according to claim 1, wherein the lower end portion of theanode member projects from the lower surface of the anode body.
 5. Asolid electrolytic capacitor, comprising: a capacitor element includingan anode body, an anode member buried in the anode body, a dielectriclayer, an electrolyte layer formed on the dielectric layer, and acathode layer formed on the electrolyte layer, the anode member having alower end portion exposed at a lower surface of the anode body, thedielectric layer being formed on part of a surface of the anode bodythat is in a region different from a region where the anode bodycontacts the anode member; an outer package member covering thecapacitor element; an anode terminal electrically connected to the lowerend portion of the anode member, and having a surface partially exposedat a lower surface of the outer package member; and a cathode terminalelectrically connected to the cathode layer at a position below thelower surface of the anode body, and having a surface partially exposedat the lower surface of the outer package member, wherein the anodemember extends in a predetermined direction along the lower surface ofthe anode body, the respective surfaces of the anode and cathodeterminals exposed at the lower surface of the outer package member arespaced apart from each other in the same direction as the predetermineddirection, and part of the anode member is opposite the exposed surfaceof the cathode terminal.
 6. The solid electrolytic capacitor accordingto claim 5, wherein the anode body has an outer circumference includinga first side surface and a second side surface substantially oppositeeach other, the anode member extends between the first and second sidesurfaces, and includes a first edge surface and a second edge surface,the first edge surface being exposed at the first side surface and thesecond edge surface existing between the first and second side surfaces,and the cathode layer and the cathode terminal are electricallyconnected to each other below a region of the lower surface of the anodebody, the region being defined between the second edge surface and thesecond side surface.
 7. A solid electrolytic capacitor, comprising: acapacitor element including an anode body, an anode member buried in theanode body, a dielectric layer, an electrolyte layer formed on thedielectric layer, and a cathode layer formed on the electrolyte layer,the anode member having a lower end portion exposed at a lower surfaceof the anode body, the dielectric layer being formed on part of asurface of the anode body that is in a region different from a regionwhere the anode body contacts the anode member; an outer package membercovering the capacitor element; an anode terminal electrically connectedto the lower end portion of the anode member, and having a surfacepartially exposed at a lower surface of the outer package member; and acathode terminal electrically connected to the cathode layer at aposition below the lower surface of the anode body, and having a surfacepartially exposed at the lower surface of the outer package member,wherein the anode terminal includes an upper stage part and a lowerstage part, the upper stage part has an upper surface electricallyconnected to the lower end portion of the anode member, and a lowersurface covered with the outer package member, and the lower stage parthas a lower surface exposed at the lower surface of the outer packagemember.